A new study has observed degenerative changes in auditory structure and function in mice and humans with Friedreich ataxia (FA).
The study, published in the Annals of Clinical Translational Neurology, found that these changes mirrored disease progress and therefore might be useful as a biomarker of disease progression.
“While sound detection is typically normal or near normal, the majority of affected individuals show progressively disordered firing in the auditory nerve and central auditory pathways (i.e., auditory neuropathy),” the authors wrote. “An appropriate mouse model could help determine if auditory function is a reliable marker for onset and progression of the disease and provide a model for testing treatments and interventions.”
The research team employed 8 FA phenotype mice and 8 wild-type control mice for the study. They assessed auditory function in the mice using otoacoustic emissions and audio steady-state responses. After 12 months, motor deficits in the mice were evaluated by rotarod testing.
Thirty-seven patients with FA underwent auditory-evoked potential assessment and the results were compared with speech perception-in-noise. Disease status was also assessed via the FA Rating Scale.
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The results revealed altered auditory-evoked potentials reflecting axonopathy and loss of spiral ganglion nerves in the mice, and reduced brainstem-level potentials in the patients. In the patients, the response amplitude correlated with auditory perception and disease status.
Compared with control mice, the FA mice had progressively increasing amplitude reductions over the course of the study. This result is similar to the progressive reduction in auditory-evoked potential amplitude observed in human patients with FA.
The authors conclude that auditory measures of axonopathy and functional changes in a mouse model of FA could serve as a model to assess treatments for this disease. In addition, these measurements could serve as a biomarker of disease progress in patients.
Reference
Rance G, Carew P, Winata L, Sale P, Delatycki M, Sly D. Auditory neuropathy in mice and humans with Friedreich ataxia. Ann Clin Transl Neurol. Published online April 14, 2023. doi.10.1002/acn3.51777
